Angular Unit/E2E testing with protractor and jasmine

Question

I am writing an angular application, whereby my controller calls an API, that returns live data which I then display on my html doc.

I am using Protractor for my end to end tests, and jasmine for unit testing.

I am mocking my API call, to ensure the API is not called.

My question is whether I should be testing the API call with protractor, and check whether my html doc is updated following the GET request, or whether I should test the API call when conducting my unit tests with jasmine.

I have a feeling that the answer is that I should be testing this API call with both my unit and end to end tests, but am hoping someone on SO can provide clarity.

Answer 1

The main goal of unit testing is to test that your code (be it JavaScrip or otherwise) is doing what it should. Each test should be done against data that static or contrived and should never be run against an API. Static data gives you the control you need. If your code needs to branch when X equals 7, you can purposely set that value and verify that your code does indeed branch. When you run against an API you do not have that control. Even if you are the one that controls the API, doing unit testing against it is a bad habit to get into.

End to end testing is completely different. Here we are not testing that the code works on a granular level (we already did that in our unit tests) we are testing that the application works as a whole. When a specific button is clicked in the application, did the expected things happen? Do all of the expected elements appear on the page? You still need to be testing against known data, and doing that is just as crucial as in unit testing, but here you get to see how your app reacts against when running. Did a particular screen take too long to load? Did a button click not give you what you expected? This kind of testing lets you click through your application as a user would (except much faster.)

You should run both kinds of tests on your app. Unit tests should be run during the build process, and end to end tests should be run once the build completes.